In recent years there has been an increasing need for composite materials having high fracture toughness, hardness and wear resistance for use in cutting tools, wear parts, and structural applications such as, dies, turbines, nozzles, etc. Due to their high modulus of elasticity, high hardness, and high strength single crystal whiskers of such materials as carbides, nitrides, or carbonitrides of titanium, zirconium, hafnium, niobium, tantalum, or tungsten could present attractive materials for composite technology. However, prior to the present invention, apparatus for producing such whiskers in commercial quantities has not been known.
Known laboratory methods for producing whiskers of metal carbides or nitrides involve placing a suitable substrate material for whisker growth at the center of a quartz tube, heating the substrate material to a temperature suitable for whisker growth, flushing the reactor tube with hydrogen, and flowing the reactant gases through the heated reactor to form whiskers on the substrate material. The prior art has presented the disadvantages of contamination of the whiskers by impurities emanating from the hot quartz tube, decomposition of the reactants subjected to heating before reaching the substrate material, and a severe limitation on the quantity of whisker production in such reactor arrangements.